Antioxidants and Antioxidant Enzymes in Higher Plants

A special issue of Plants (ISSN 2223-7747). This special issue belongs to the section "Phytochemistry".

Deadline for manuscript submissions: closed (31 December 2023) | Viewed by 6808

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Department of Biology, University of Naples “Federico II”, 80126 Naples, Italy
Interests: bioindicators; aquatic mosses; biomarkers; antioxidant enzyme; DNA damage; ROS; stress- genes; heavy metals; environmental pollution
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Dear Colleagues,

Reactive oxygen species (ROS) within a cell can be produced at different cellular levels, as a result of various metabolic processes. In physiological conditions, the production and removal of reactive species are finely controlled processes that maintain the balance of the redox state. However, this balance can disrupted when ROS are synthesized in excess, e.g., in stressful scenarios. The defense systems that cells possess can be non-enzymatic and enzymatic. Among the non-enzymatic components, certain molecules are of great importance, including ascorbate, glutathione, tocopherol, carotenoids and phenolic compounds. The ability of plants to modulate ROS production in the presence or absence of stress is also due to the activity of enzymes that use ROS as substrates. These enzymes are superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX), which belong to the group of enzymes involved in the metabolism of ROS. Other important enzymes, albeit with an indirect role, are monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHA), glutathione reductase (GR), ascorbate and glutathione.

The aim of this Special Issue is to present advances in the research on enzymatic and non-enzymatic antioxidant responses and defense mechanisms of plants to oxidative stress, bringing together high-quality original research papers, brief communications and reviews by leading scientists in this field of research.

Dr. Viviana Maresca
Guest Editor

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Keywords

  • antioxidant enzymes
  • non-enzymatic components
  • oxidative stress
  • molecular responses
  • abiotic stress
  • defense systems

Published Papers (3 papers)

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Research

17 pages, 2551 KiB  
Article
Antioxidant and Antifungal Activities and Characterization of Phenolic Compounds Using High-Performance Liquid Chromatography and Mass Spectrometry (HPLC-MS) in Empetrum rubrum Vahl ex Willd.
by Carlos Schneider, Makarena González-Reyes, Carola Vergara, Camila Fuica-Carrasco and Patricio Zapata
Plants 2024, 13(4), 497; https://doi.org/10.3390/plants13040497 - 09 Feb 2024
Viewed by 819
Abstract
In searching for compounds with antioxidant and antifungal activity, our study focused on the subshrub species Empetrum rubrum Vahl ex Willd. (Ericaceae). We measured the antioxidant activity of its methanolic extract (MEE) obtained from the aerial parts (leaves and stems) and of its [...] Read more.
In searching for compounds with antioxidant and antifungal activity, our study focused on the subshrub species Empetrum rubrum Vahl ex Willd. (Ericaceae). We measured the antioxidant activity of its methanolic extract (MEE) obtained from the aerial parts (leaves and stems) and of its methanolic extract (MEF) obtained from the lyophilized fruits. The antioxidant activity of the MEE and MEF was evaluated in vitro via a 2,2-Diphenyl-1-picrylhydrazyl (DPPH) free radical and 2,2′-Azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) cationic radical. The results were expressed in gallic acid and Trolox equivalents for the DPPH and ABTS assays, respectively. The antioxidant activities, for the DPPH and ABTS assays, were also evaluated by considering the IC50 values. Concerning the antioxidant activity, the total phenolic content (TPC) in the MEE and MEF was determined using the Folin–Ciocalteu method. Polyphenols contained in the leaves, stems, and fruits of E. rubrum were determined qualitatively by employing high-performance liquid chromatography coupled with mass spectrometry (HPLC-MS) analysis. The antifungal activity of the MEE obtained from the aerial parts of E. rubrum was tested against Rhizoctonia solani. The results of IC50 values measured by the DPPH and ABTS methods with MEE were 0.4145 ± 0.0068 mg mL−1 and 0.1088 ± 0.0023 mg mL−1, respectively, and the IC50 values for MEF were 6.4768 ± 0.0218 mg mL−1 and 0.7666 ± 0.0089 mg mL−1 measured by the DPPH and ABTS methods, respectively. The HPLC-MS analysis revealed the presence of anthocyanins, phenolic acids derivatives, and flavonols. In vitro, mycelial growth of this fungus was reduced from 90% to nearly 100% in the presence of MEE. The observed antifungal effect is related to the presence of the abovementioned phenols, detected in the MEE. Full article
(This article belongs to the Special Issue Antioxidants and Antioxidant Enzymes in Higher Plants)
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18 pages, 4061 KiB  
Article
Response of Maize Seedlings to Silicon Dioxide Nanoparticles (SiO2NPs) under Drought Stress
by Asmaa A. Sharf-Eldin, Khairiah Mubarak Alwutayd, Ahmed Abou El-Yazied, Hossam S. El-Beltagi, Basmah M. Alharbi, Mohammad A. M. Eisa, Mohammed Alqurashi, Mohamed Sharaf, Nadi Awad Al-Harbi, Salem Mesfir Al-Qahtani and Mohamed F. M. Ibrahim
Plants 2023, 12(14), 2592; https://doi.org/10.3390/plants12142592 - 08 Jul 2023
Cited by 6 | Viewed by 3262
Abstract
Recently, the use of nanofertilizers has received a great deal of attention in managing plants under biotic and abiotic stresses. However, studies that elucidate the role of silicon dioxide nanoparticles (SiO2NPs) in regulating maize tolerance to drought stress are still at [...] Read more.
Recently, the use of nanofertilizers has received a great deal of attention in managing plants under biotic and abiotic stresses. However, studies that elucidate the role of silicon dioxide nanoparticles (SiO2NPs) in regulating maize tolerance to drought stress are still at early stages of development. In this study, plants that were treated with SiO2NPs (0.25 g/L as foliar spray) displayed considerable improvement in the growth indices, despite being subjected to drought stress. In addition, the action of SiO2NPs led to a considerable rise in the levels of chlorophylls, proline, cell membrane integrity, leaf water content, and antioxidant enzymes (superoxide dismutase (SOD), catalase (CAT), and guaiacol peroxidase (G-POX)). In contrast, an inverse trend was seen in the oxidative injury, the total amount of soluble sugars, and the activity of ascorbate peroxidase (APX). At the same time, carotenoids were unaffected in SiO2NPs-treated and non-treated plants under drought stress. The results of the molecular investigation that was conducted using qRT-PCR showed that the relative expression of the D2 protein of photosystem II (PsbD) was elevated in SiO2NPs-treated plants in response to drought stress, while the expression of the osmotic-like protein (OSM-34) and aquaporin (AQPs) was downregulated in SiO2NPs-treated plants in response to drought stress. This research could pave the way for further investigations into how SiO2NPs boost plant resistance to drought stress. Full article
(This article belongs to the Special Issue Antioxidants and Antioxidant Enzymes in Higher Plants)
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16 pages, 1983 KiB  
Article
Moringa Leaf Extract Mitigates the Adverse Impacts of Drought and Improves the Yield and Grain Quality of Rice through Enhanced Physiological, Biochemical, and Antioxidant Activities
by Shahbaz Khan, Danish Ibrar, Zuhair Hasnain, Muhammad Nawaz, Afroz Rais, Sami Ullah, Safia Gul, Manzer H. Siddiqui and Sohail Irshad
Plants 2023, 12(13), 2511; https://doi.org/10.3390/plants12132511 - 30 Jun 2023
Cited by 3 | Viewed by 1756
Abstract
Agriculture, around the globe, is facing great challenges including the need to increase the production of nutrient-dense food and to withstand climate change’s impact on water and soil conservation. Among these challenges, drought stress is considered the most overwhelming danger for the agriculture [...] Read more.
Agriculture, around the globe, is facing great challenges including the need to increase the production of nutrient-dense food and to withstand climate change’s impact on water and soil conservation. Among these challenges, drought stress is considered the most overwhelming danger for the agriculture sector. Organic plant growth ingredients are frequently used to enhance the growth and production of field crops cultivated in normal and unfavorable conditions. The present study was designed to explore whether leaves extracted from various landraces of Moringa could play a defensive role against drought stress in rice. Seedlings were grown under three water conditions, i.e., normal conditions (control; 100% field capacity), moderate (75%), and severe drought (50%). Leaf extracts obtained from four Moringa landraces were used as foliar spray at the tillering, panicle initiation, and grain filling stages of cultivating rice plants. The levels of water stress negatively influenced photosynthetic pigment synthesis, gas exchange traits, antioxidant activities, and yield and grain quality parameters. Leaf extracts, at the rate of 3%, from all the landraces significantly enhanced the biochemical, physiological, and yield-related attributes of rice plants under normal and unfavorable growth conditions. Particularly, leaf extract from the Faisalabad landrace was the most effective biostimulant to increase photosynthetic (8.2%) and transpiration (13.3%) rates, stomatal conductance (8.3%), chlorophyll a (15.9%) and b (9.7%) contents, and carotenoids (10.4%) as compared to water spray. The maximum photosynthesis rate was observed at 14.27 µmol CO2 m−2 s−1 via application of leaf extract from the Faisalabad landrace followed by the DG Khan (13.92 µmol CO2 m−2 s−1) and Multan (13.9 µmol CO2 m−2 s−1) landraces, respectively. Improved grain yield (25.4%) and grain quality (an increase of 10.1% in amylose with a decrease of 2.8% in amylopectin) in rice plants along with enzymatic activities such as catalase (21.2%), superoxide dismutase (38.6%), and ascorbate peroxidase (24.3%) were observed at the peak after application of leaf extract from the Faisalabad landrace. The maximum grain yield of 53.59 g per plant was recorded when using Faisalabad landrace leaf extract and the minimum (40 g) using water spray. It is concluded from the findings of the current experiment that leaf extract from the Faisalabad landrace possesses higher biostimulant potential than other landraces and can be applied to mitigate the adverse impacts of drought stress with higher productivity and improved grain quality of rice. Full article
(This article belongs to the Special Issue Antioxidants and Antioxidant Enzymes in Higher Plants)
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